Heretofore, water repellent properties have been imparted to inorganic building materials by applying solutions containing organosilicone compounds and an organic solvent, such as a hydrocarbon solvent, to at least part of the surface of the building materials which are to be rendered water repellent. U.S. pat. No. 4,342,796 to Brown et al, for example, describes a method for treating reinforced concrete by applying a hydrolyzable organosilicon compound to the surface of the reinforced concrete and thereafter contacting the organosilicon coated surface with an effective amount of water to substantially wet the surface of the organosilicon impregnated structure.
U.S. Pat. No. 3,819,400 to Plankl et al describes a method for treating porous substrates to render them water repellent by hydromechanically treating the porous substrates and thereafter applying a solution of one or more organosilicon compounds in a C.sub.2 to C.sub.4 alkanol to render the porous substrates hydrophobic.
In the methods described above, the substrates were substantially dry or when the substrates are moist, they were treated with organosilicon compounds dissolved in short chain alkanols as the organic solvent.
The brochure "Wacker silicone, Silicone Masonry Water Repellents" SME-8-142.8011 recommends that an organosiloxane in an organic solvent be diluted with aromatic or aliphatic hydrocarbons, i.e., with a water-immiscible solvent. The pamphlet also sttes that the effect on slightly wet areas is also good; however, the brochure does not indicate that better results are obtained with a wet surface over those obtained with a dry surface.
Therefore, it is an object of the present invention to provide a method for imparting water repellency to absorbent inorganic building materials. Another object of the present invention is to provide a method for imparting water repellency to inorganic building materials by treating the building materials with solutions containing organosilicone compounds and water-immiscible organic solvents. Another object of the present invention is to provide a method for imparting water repellency to inorganic building materials which requires only a small quantity of an organosilicone compound. Still another object of the present invention is to provide a method for imparting water repellency to inorganic building materials in which the organosilicone compound deeply penetrates into the treated building material. A further object of the present invention is to provide a method for imparting water repellency to inorganic building materials, in which water is absorbed very slowly into the treated building materials.